This invention relates to a starting fuel increasing system for internal combustion engines and more particularly to an improved cold starting mechanism for such engines.
As is well known, it is desirable, if not essential, to provide an enriched mixture for starting and cold running of internal combustion engines. Such an enriched mixture is necessary not only to insure good starting but to insure stable operation at idle and during running when the engine is cold. Two basic type of cold starting and cold running enrichment devices have been employed. One uses a choke valve in the intake passage having a valve element that is moved between a closed and opened position in response to temperature variations to provide the enrichment. The choke valve may be controlled either by an electrically operated system or by means of a bimetallic element. However, such devices are not completely satisfactory because it is difficult to accurately match the opening of the choke valve with the actual running temperature of the engine. Furthermore, it is often difficult to provide both the necessary degree of enrichment during cranking and the required fuel/air mixture during cold running. In addition, choke valves have other well known disadvantages.
As another form of cold starting and cold enrichment device, it has been proposed to provide a starting fuel circuit in the charge forming device for the engine. Such cold starting circuits include an enrichment fuel passage and a valve that is disposed in the enrichment fuel passage and which is movable between a closed, normal running condition and an opened, cold enrichment condition. However, the discharge of such systems is dependent upon the intake manifold vacuum or the vacuum at the point of discharge, which can vary widely during running conditions. Furthermore, the amount of vacuum generated by the engine during cranking may not be sufficient to provide the requisite degree of enrichment during cold starting.
It is, therefore, a principal object of this invention to provide an improved starting fuel increasing system for internal combustion engines.
It is another object of this invention to provide an improved and simplified cold starting and cold running enrichment device for internal combustion engines.
It is a yet further object of this invention to provide a cold starting enrichment device for engines that provides the requisite amount of fuel for cold starting and also an appropriate amount of fuel for good cold running performance.